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285/645R18 Continental's, air pressure

I just bought a set of these. Wondering what you guys set the air pressure at cold, and what they should be at when they are warm.
cosm3os said:
38-39 hot. 28 or so cold is a good start, but the best way to know is the get em hot and bleed them down.

+1 Also depends on the track temp and how hard and long you run them in a session. It was cool in Charlotte and I was only able to get the tire pressures to rise around 6 pounds on all but one session in which I got a lot of clear track to run on.
They'll go hotter. Use the hot pressures to get the car handling then let them cool overnight and you'll have a new set of starting pressures. I would advise using nitrogen or at least dehumidified air because the any moisture in the tire can cause the pressures to vary widely including "spiking". Don't be afraid to run different pressures at all 4 corners to get the car to work.
At that point you'll need some expensive gauges and / or a guy like me to take you further.
Here is what I received directly from Hoosier last year. I found the GTO's worked well at 38 - 40 hot.

275/35R-18 EC(Extreme Contact) – Dry

285/645R-18 GT-O

The EC-Dry tire would need 30 – 32 psi COLD / 40 – 42 psi HOT pressures

The GT-O tire would need 24 – 26 psi COLD / 32 – 43 psi HOT pressures.


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my 305/660R18 GT-O's like 36 hot the best, but they do well up to 38, where they start to fall off. they turn into Crisco at 40.
Again, and this is vital, you need to use either dehumidified air or nitrogen, at the upper levels moisture in the tire over 20% will cause the air pressure to spike, this could be adding to the high pressures, if this is happening in one or two tires or not the other you will never get the setup right.

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